A computer program listing appendix is submitted on compact disk and is hereby incorporated by reference. A total of two compact discs are submitted as part of the computer program listing appendix. Each compact disc contains an identical copy of the file 10992699.doc, created on Nov. 6, 2002 and containing 104,222 bytes.
The present invention concerns automated process control and pertains particularly to use of intelligent logic activity resolution within an automated process control system.
Current methods of automated manufacturing process control are limited by the use of static connected state transition models to impose a predefined behavioral expectation on the process.
In a standard state transition model, each state can only transition to a limited number of other states based on fixed transition events. For example, a manufacturing process in a first state can only transition to a second state upon the occurrence of a first transition event or into a third state upon the occurrence of a second transition event. All other states and transition events are considered invalid. Under this static state transition process model, if, while in the first state, a third transition event occurs, the model will not be able to determine a next valid state. Instead, the system would, for example, issue an alarm and halt the manufacturing process.
An additional limitation to automated manufacturing process control systems that function in accordance with a standard state transition model is the static nature of the state model. There is no provision for the system to adapt itself to new states and transition events without significant manual intervention.
In accordance with the preferred embodiment of the present invention, intelligent logic activity resolution (ILAR) is provided for a process. Upon a first trigger event being received, a first subset of conditions of the process is detected. The first subset of conditions is selected based on the first trigger event. When the first subset of conditions match predetermined values, a first state is entered. When the first subset conditions do not match the predetermined values, additional conditions are checked. On the basis of the checked additional conditions, a new state is selected for entry.
In the preferred embodiment, the detection of the first subset of conditions is done by running a separate metaprocedure to detect each condition in the first subset of conditions. A metaprocedure is a software function that performs an automated check for a condition. A metaprocedure can also perform non-state change related functions such as sending messages to external systems, or storing and retrieving data variables relevant to the process. In the preferred embodiment, each condition is represented with a single metaprocedure.
In a preferred embodiment of the present invention, the subset of conditions are also selected based on a current state of the process.
Upon receiving a second trigger event, a second subset of conditions of the process are detected. The second subset of conditions are selected based on the second trigger event. When the second subset of conditions match predetermined values, a corresponding state is entered. When the second subset of conditions do not match the predetermined values, additional conditions are checked. On the basis of the checked additional conditions a new state is selected for entry.
The ILAR system described herein removes the constraints of the static connected state transition model. The ILAR system disconnects the state and transition event relationship and treats each state and transition event as a unique and independent occurrence. Using a dynamic, real time logic engine, rather than a static connected state model, the ILAR heuristically determines the next state based on an analysis of all detectable manufacturing process conditions rather than the transition event detected. With this method, all states and transitions are always valid, unless specifically declared invalid by the user. This is a significant advance over prior art state machines.